This isn’t how it was supposed to go. Of course Novak Djokovic and Rafael Nadal were forgone conclusions for the semifinals of the U.S. Open—they were the top two seeds and have a combined 18 Grand Slam titles between them. Reigning Wimbledon champ Andy Murray and French Open runner-up David Ferrer (who has reached the semis in three of the last four Majors) were expected to join them. But Richard Gasquet and Stanislas Wawrinka? Not so much. Both are Top-10 players, but they have just one Grand Slam semifinal appearance between the two of them (Gasquet lost to Roger Federer in straight sets at the 2007 Wimbledon Championships). On Saturday, it’s up to them to bring down the best tennis players in the world.

Though Gasquet and Wawrinka are just 27 and 28, respectively, it feels like they’ve been around for a long time. Gasquet played his first Grand Slam at Roland Garros in 2002. Wawrinka made his debut there three years later. Expectations were high for both players when they turned pro, but neither has truly broken through.

Gasquet—initially expected to lead the resurgence of French tennis along with Jo-Wilfried Tsonga and human highlight reel Gael Monfils—reached a career-best 7th in the ATP rankings after his semifinal berth at the All-England Club, but couldn’t capitalize on that momentum. He suffered injuries in 2008 and 2009 before testing positive for cocaine midway through the 2009 season. His spectacular defense strategy, which stated that he only tested positive because he kissed a woman who had taken cocaine at a nightclub, paid off. The Court of Arbitration for Sport cleared Gasquet of any wrongdoing. But for the most part, Gasquet was unable to capitalize on his second chance. He was ranked 52nd by the end of 2009 and though he has climbed all the way back to No. 8 in the world, he did not advance beyond the fourth round of a Grand Slam tournament until beating No. 10 Milos Raonic in an exhausting five-setter on Tuesday.

Less than 48 hours later, the Frenchman took down Ferrer in the quarterfinals. That match proved no less grueling than his previous one: Gasquet broke out to a two-sets-to-love lead, but Ferrer came storming back to force a fifth set. Somehow, Gasquet recaptured the momentum and defeated the fourth-seeded Spaniard in the fifth set. Gasquet’s triumphs will mean little when he meets Nadal on Saturday. The 12-time Grand Slam champ is 10-0 lifetime against Gasquet, though the two haven’t met on hard court since Nadal dispatched Gasquet effortlessly in the opening round of the 2009 U.S. Open. On top of that, Nadal is playing some of the best hard court tennis of his life right now: he’s a perfect 20-0 on the season and hasn’t been broken once in 67 service games at the tournament. Couple his punishing style of play with Gasquet’s recent marathon matches and you start to get an idea of just how long the odds are for Gasquet.

Perhaps in slightly better position is Wawrinka, who is fresh off a dominant straight-set victory over Andy Murray in the quarterfinals. Wawrinka, a Lausanne, Switzerland native, has spent virtually all of his career in the shadows of countryman Roger Federer—this is the first Grand Slam event in which Wawrinka has outlasted Federer. He’s made a smattering of quarterfinals in Grand Slams, beginning with his first at the 2010 U.S. Open, but has struggled to find consistency in his all-around game that matches his formidable backhand. That’s changed in 2013, with Wawrinka enjoying the best season of his career. He’s 36-15 this year and may finally be close to putting all the pieces together at 28. His win against Murray certainly demonstrated another step forward, though it likely would have a different match entirely if the same Murray who won in Flushing last year showed up. Instead, Wawrinka got the Murray of old—the one who spends matches oscillating between listless and furious. That Murray was no match for Wawrinka’s relentless approach—he tallied 45 winners to Murray’s 15.

But Novak Djokovic is not Andy Murray. Djokovic has bludgeoned his way through the top half of the draw. He’s dropped just one set (in Friday’s quarterfinal against Mikhail Youzhny, and even that seemed like it only happened because Djokovic was unaware the match was still going on—he bagel’d Youzhny in the fourth and final set) and has looked like his usual, unbeatable self. Djokovic is also 12-2 lifetime against Wawrinka, who hasn’t beaten the world’s No. 1 since they met in Vienna over seven years ago. But the last time they squared off, in the fourth round of this year’s Australian Open, Wawrinka pushed Djokovic, who later won the title, in a five-hour, five-set marathon. They could be headed for an encore performance.

In all likelihood, Saturday will unfold the way it’s supposed to, with Nadal and Djokovic moving on to face each other in the final on Monday afternoon and Gasquet and Wawrinka heading home with best-ever showings. But tennis can be funny. The raucous crowds and swirling winds make the U.S. Open the most unpredictable of the four Grand Slams. So maybe these tennis giants can be felled. Either way, we’re in for a wild semifinal Saturday.